Satellites in geostationary orbit (GSO) have been widely preferred for several decades because of economic advantages. In a geostationary orbit, a satellite traveling above the Earth's equator, in the same direction as that in which the Earth is rotating, and at the same angular velocity, appears stationary relative to a point on the Earth. These satellites are always “in view” at all locations within their service areas. Antennas on Earth need to be aimed at a GSO satellite only once; no tracking system is required.
Coordination between GSO satellites generally occurs on a first-come, first-served, basis; such coordination sometimes is facilitated by governmental allocation of designated “slots” angularly spaced according to service type.
Given the desirability of geostationary satellite orbits and technical limits in spacecraft and earth station design, the number of satellites that can effectively serve a given area on the earth using a particular band of operation (e.g., “C-band”, or “Ku-band”) is limited. While efforts have continued to improve the technology to enhance capacity, governments have on occasion resorted to auctions as a mechanism to assign limited orbital resources where the demand has exceeded the apparent supply. These circumstances have encouraged the development of complex and expensive new systems including those using low Earth orbit (LEO), medium Earth orbit (MEO), and higher frequencies, for example, the Ka band (up to approximately 40 GHz). Growth to higher frequencies is limited by problems of technology and propagation: thus some efforts at expanding satellite applications involve exploitation of the spatial dimension (i.e., utilizing satellite orbits other than the GSO). A host of proposed LEO and MEO systems exemplify this direction.
The recently filed LEO and MEO system applications, however, introduce additional technical complexity and costs that may not be justified in some applications. Frequency coordination and sharing are complicated by the unstructured crisscrossing of the lines of sight of these systems.
In the use of geostationary orbits, objectives in establishing networks is to maximize the independence between satellites. To achieve this, the burden of coordination is placed on the later entrant, to ensure interference-free operation vis-à-vis existing systems. Because of the number of networks in operation, particularly in the heavily utilized C-band and Ku-band, interference-free capacity is very difficult (if not impossible) to coordinate for service areas including the populated land masses. It would therefore be desirable to provide a system for coordinating various satellite operations so that the aggregate communications capacity of all satellites may be improved, and the overall utilization of the resource is increased. It would therefore be desirable to provide a system for coordinating various satellite operations so that the aggregate communications capacity of satellites may be maximized.